The present invention generally relates to RF emitter direction finding methods, and more particularly, to methods that estimate the angle of arrival of an RF agile signal using a long baseline interferometer, and that resolves phase ambiguities to provide for unambiguous angle of arrival estimation from the measured phase.
Heretofore, because measured phase is highly ambiguous, long baseline interferometers have been used to measure the phase rate over time of a received signal. Change in phase rate is used to estimate the location of the RF emitter. An independent angle measurement may be used to estimate the phase ambiguity. However, the accuracy required of the independent measurement is typically impractical to implement.
Therefore, it is an objective of the present invention to provide for a direction finding method that unambiguously estimate the angle of arrival of an RF agile signal using a long baseline interferometer, and resolve phase ambiguities to provide for unambiguous angle of arrival estimation from the measured phase.